Date   : Wed, 27 Jul 2005 15:50:59 +0200 (BST)
From   : Johan Heuseveldt <johan@...>
Subject: Re: Econet-Ethernet bridge

Hi Jules,

On Wed 27 Jul, Jules Richardson wrote:

[snip]

> The only critical thing is what interface to use between the Econet
> module and the PC. PCI and ISA are probably dead ends for the reason of
> changing times as mentioned before. That probably leaves SCSI, USB,
> serial and parallel. 
> 
> SCSI's not available on enough machines for it to be viable. USB's only
> on newer hardware, whilst serial is sometimes only available on older
> hardware. Parallel seems to be everywhere, but may well be far too slow
> to drive a module.

Iyonix computer doesn't have a parallel port anymore. New printers also
seem to come without one (only USB and/or network). So I doubt if parallel
will be as standard in a few years time, as it is still to day. Certainly
there is something going on!

The fastest clock speed for Beebs is about 190-200 kHz. An Elk (Electron)
can't cope with that. Clock box Iss 2 from Acorn (black with green logo)
wil go as fast as 500 kHz, which works perfectly on 32 bits machines like
A5000, though I haven't tested this (yet) with an Archimedes with an ARM2
processor.

The speeds involved here for Econet are in the region of floppy discs.

Also, the wave form has sharp edges, rectangular by design. Modern digital
signals are leaning quite heavily on new analogous signal curves,
consideribly increasing the speed. ADSL is a good example. So no doubt,
the old and current Econet speeds are already at maximum.

Not sure about normal Centronics interface, but modern ones are classified
as fast (faster handshaking) and allow for buffering in their dedicated
chips as well, also increasing the overall speed.

So, Econet for Beebs is at max 200 kHz, which is bit speed. Byte speed
will then, lets say, 20 to 25 kHz. (20/10, 20/9, 20/8)
Is that (really) a problem for parallel/Centronics?

Hope this helps.


greetings,
Johan

-- 
Johan Heuseveldt <johan@...              >
  aka  waarland

  The best place is a Riscy place
 
If you can keep your head when all about you are losing
theirs, you must be at least a foot shorter than them.